# Creating a custom plugin for Apache Airflow PythonVirtualenvOperator
The following sample explains how to patch the Apache Airflow `PythonVirtualenvOperator` with a custom plugin on Amazon Managed Workflows for Apache Airflow.
**Topics**
+ [Version](#samples-virtualenv-version)
+ [Prerequisites](#samples-virtualenv-prereqs)
+ [Permissions](#samples-virtualenv-permissions)
+ [Requirements](#samples-virtualenv-dependencies)
+ [Custom plugin sample code](#samples-virtualenv-plugins-code)
+ [Plugins.zip](#samples-virtualenv-pluginszip)
+ [Code sample](#samples-virtualenv-code)
+ [Airflow configuration options](#samples-virtualenv-airflow-config)
+ [What's next?](#samples-virtualenv-next-up)
## Version
You can use the code example on this page with **Apache Airflow v2** in [Python 3.10](https://peps.python.org/pep-0619/) and **Apache Airflow v3** in [Python 3.11](https://peps.python.org/pep-0664/).
## Prerequisites
To use the sample code on this page, you'll need the following:
+ An [Amazon MWAA environment](get-started.md).
## Permissions
No additional permissions are required to use the code example on this page.
## Requirements
To use the sample code on this page, add the following dependencies to your `requirements.txt`. To learn more, refer to [Installing Python dependencies](working-dags-dependencies.md).
```
virtualenv
```
## Custom plugin sample code
Apache Airflow will execute the contents of Python files in the plugins folder at startup. This plugin will patch the built-in `PythonVirtualenvOperator` during that startup process to make it compatible with Amazon MWAA. The following steps display the sample code for the custom plugin.
1. In your command prompt, navigate to the `plugins` directory in the previous section. For example:
```
cd plugins
```
1. Copy the contents of the following code sample and save locally as `virtual_python_plugin.py`.
```
"""
Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
"""
from airflow.plugins_manager import AirflowPlugin
import airflow.utils.python_virtualenv
from typing import List
def _generate_virtualenv_cmd(tmp_dir: str, python_bin: str, system_site_packages: bool) -> List[str]:
cmd = ['python3','/usr/local/airflow/.local/lib/python3.7/site-packages/virtualenv', tmp_dir]
if system_site_packages:
cmd.append('--system-site-packages')
if python_bin is not None:
cmd.append(f'--python={python_bin}')
return cmd
airflow.utils.python_virtualenv._generate_virtualenv_cmd=_generate_virtualenv_cmd
class VirtualPythonPlugin(AirflowPlugin):
name = 'virtual_python_plugin'
```
## Plugins.zip
The following steps explain how to create the `plugins.zip`.
1. In your command prompt, navigate to the directory containing `virtual_python_plugin.py` in the previous section. For example:
```
cd plugins
```
1. Zip the contents within your `plugins` folder.
```
zip plugins.zip virtual_python_plugin.py
```
## Code sample
The following steps describe how to create the DAG code for the custom plugin.
1. In your command prompt, navigate to the directory where your DAG code is stored. For example:
```
cd dags
```
1. Copy the contents of the following code sample and save locally as `virtualenv_test.py`.
```
"""
Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
"""
from airflow import DAG
from airflow.operators.python import PythonVirtualenvOperator
from airflow.utils.dates import days_ago
import os
os.environ["PATH"] = os.getenv("PATH") + ":/usr/local/airflow/.local/bin"
def virtualenv_fn():
import boto3
print("boto3 version ",boto3.__version__)
with DAG(dag_id="virtualenv_test", schedule_interval=None, catchup=False, start_date=days_ago(1)) as dag:
virtualenv_task = PythonVirtualenvOperator(
task_id="virtualenv_task",
python_callable=virtualenv_fn,
requirements=["boto3>=1.17.43"],
system_site_packages=False,
dag=dag,
)
```
## Airflow configuration options
If you're using Apache Airflow v2, add `core.lazy_load_plugins : False` as an Apache Airflow configuration option. To learn more, refer to [Using configuration options to load plugins in 2](configuring-env-variables.md#configuring-2.0-airflow-override).
## What's next?
+ Learn how to upload the `requirements.txt` file in this example to your Amazon S3 bucket in [Installing Python dependencies](working-dags-dependencies.md).
+ Learn how to upload the DAG code in this example to the `dags` folder in your Amazon S3 bucket in [Adding or updating DAGs](configuring-dag-folder.md).
+ Learn more about how to upload the `plugins.zip` file in this example to your Amazon S3 bucket in [Installing custom plugins](configuring-dag-import-plugins.md).